(1) Field of the Invention
This invention relates to filters for cigarettes. In one respect, it relates to a low efficiency filter having a reduced flow path for ventilating air and smoke providing an increased pressure drop to increase the draw resistance of the filter. In another respect, the present invention relates to a filter which functions to direct the flow of smoke exiting the filter from the periphery at the mouth end of the filter.
(2) Description of the Prior Art
It is well known in the art of filter cigarettes to provide filters with ventilation means to allow ambient air to dilute the smoke traveling through the filter. The dilution of the smoke reduces the quantity of smoke particulate as well as the gas phase components which enter the smoker's mouth. For example, the outer wrapper surrounding the tobacco column can be made of a porous material which allows ventilating air to be introduced into the tobacco column along the entire length of the cigarette wherein it mixes with the smoke stream to dilute it before entering the smoker's mouth. Or, the cigarette wrapper may be perforated at selected locations along the length of the cigarette to provide ports through which ventilating air enters the cigarette. It is also known to perforate the wrapper of the filter at the filter end of the cigarette to allow ventilating air to enter the filter and dilute the smoke stream flowing through the filter. Additional suggestions have included forming grooves within the filter plug of a cigarette to facilitate the addition of ventilating air into the smoke stream. Specific examples are shown in U.S. Pat. No. 3,596,663; U.S. Pat. No. 3,577,995; U.S. Pat. No. 3,572,347; U.S. Pat. No. 3,490,461; U.S. Pat. No. 1,718,122; U.S. Pat. No. 3,788,330; U.S. Pat. No. 3,773,053; U.S. Pat. No. 3,752,165; U.S. Pat. No. 3,638,661; U.S. Pat. No. 3,608,561; and U.S. Pat. No. 3,910,288.
Further, in most commercially available cigarettes, either of the ventilated or non-ventilated type, the smoke is concentrated at the center of the mouth end of the filter as it exits the filter into the smoker's mouth thereby missing many of the "taste buds". Therefore, these cigarettes, particularly of the highly ventilated type, deliver very little taste.
It is also true in many ventilated filter cigarettes that the draw effect is substantially less than that of more conventional cigarettes which diminish the smoking pleasure.